During normal breathing, air passes through the nose and past the flexible structures in the back of the throat such as the soft palate, uvula and tongue. When an individual is awake, muscles hold the airway open, but during sleep, these muscles relax and can potentially cause problems. Sleep disordered breathing such as snoring, upper airway resistance syndrome (UARS) and obstructive sleep apnoea (OSA) are thought to occur when there is at least partial occlusion of the airway, with the tongue often being associated with the occlusion. During OSA, the tongue is sucked against the back of the throat, completely blocking the air flow. When oxygen levels in the brain become low enough, the sleeper partially awakens and the muscles contract opening the airway again. This cyclic occlusion of the airway can have serious repercussions, including contributing to cardiovascular diseases potentially leading to cardiac arrest and death.
There are a number of treatment options available including surgery, nasal continuous positive airway pressure (CPAP) and the use of orthotic devices. Orthotic devices are becoming an increasingly favoured option as they are generally small and easy to wear and relatively inexpensive. Another benefit of orthotic devices is that the treatment is reversible and non-invasive.
Mandibular advancement device (MAD) is one type of orthotic device which is used to hold the mandible in a protrusive position, which has proved effective in the treatment of sleep disordered breathing. Retaining the mandible in a protruded position has been found to help control the symptoms of sleep disordered breathing by clearing the airways and reducing the likelihood of the tongue impacting on breathing.
Boil and bite MADs are prefabricated and are lined with a soft, thermoplastic material that is moulded to the patient's teeth in the patient's home. The MAD engages the mandible mainly at the incisors and therefore applies the force of advancement across only a couple of teeth. While these MADs are relatively cheap and easy to use, they have the disadvantage in that they can potentially apply excessive force to the lower anterior teeth in some patients and this can cause discomfort, movement of the teeth and problems with the fit of the device over time. Another potential problem is that they are not adjustable once moulded to the patient, limiting their applicability to a wider range of patients. Furthermore, some patients may not have healthy gums and teeth in both the upper and lower jaws upon which to brace the MAD in the mouth.
Another example is a laboratory fabricated MAD which requires the attendance of a dentist to take mouth impressions which are used to make models of the teeth and gums. These moulds are then used to make dental overlays to overlay all of the lower and upper teeth, and protrude the mandible and help to clear the airways. A laboratory fabricated MAD can also cause excessive force on the teeth, leading to pain and tooth movement. Moreover, laboratory fabricated MADs can be problematic to customize to the patient's dental requirements as they require both healthy gums and teeth.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.